The BOOST symbol is wild and can substitute for another symbol in the payline. Every time the BOOST symbol is going to appear, the game is interrupted and you can select either to keep the current bet placed or "boost" your bet 10 times (you "boost" your bet by clicking the smaller lever). This allows amazing winnings per single spin. Also, no bet is lost at the Booster game. Every bet which does not win is added to the special Fund. The Fund can be cashed anytime for 10% of its value or you may choose to try to recover ALL of your bets by risking and attempting to win the entire amount during a special WIN/LOSE spin.